1. Field of the Invention
The present invention relates to a member (hard surface member) having a hard coating such as a sliding component of a machine, and a cutting tool.
2. Description of the Related Art
An amorphous carbon film is known as a hard coating. Amorphous carbon has an intermediate structure between diamond and graphite carbon being mixed with each other, and may be called hard amorphous carbon, formless carbon, hard formless carbon, i-carbon, or diamond like carbon (DLC). Since the amorphous carbon (hereinafter, sometimes called DLC) has high hardness as diamond, and has excellent wear resistance, solid lubricating ability, heat conductivity, and chemical stability, it is being used for protective films for various components such as sliding members, dies, cutting tools, wear-resistant machine parts, abradants, and magnetic/optical components. In particular, the amorphous carbon (DLC) is practically used for a coating of a cutting tool for an aluminum or cupper material by making a use of properties of the amorphous carbon (DLC) such as chemical inertness, and less reactiveness with nonferrous metals. However, on the other hand, the excellent chemical stability of an amorphous carbon (DLC) film means low adhesion of the film to various kinds of substrates.
To improve adhesion between the amorphous carbon (DLC) film and a substrate, it has been proposed that an intermediate layer is formed between the amorphous carbon (DLC) film and a substrate (Japanese Patent Laid-Open No. H8-74032 (claims and paragraph 0007), Japanese Patent Laid-Open No. 2003-171758 (claims) and the like). In Japanese Patent Laid-Open No. H8-74032 (claims and paragraph 0007), when carbon is evaporated on a substrate, an inert gas is irradiated on the substrate, thereby a mixed layer (metal carbide layer or ceramic carbide layer) including a substrate material (metal or ceramics) and carbon is formed, then the amorphous carbon (DLC) film is formed. Japanese Patent Laid-Open No. 2003-171758 (claims) proposes an intermediate layer having a 4-layer structure, in which a metal layer of Cr/Al is formed as a first layer, then a mixed metal layer of Cr/Al and W/Ta/Mo/Nb is formed as a second layer, and then a metal layer of W/Ta/Mo/Nb is formed as a third layer, and then a carbide layer of W/Ta/Mo/Nb is formed as a fourth layer. Both of the carbide layers in JP-A-8-74032 (claims and paragraph 0007) and JP-A-2003-171758 (claims) show an intermediate composition between the substrate and the amorphous carbon (DLC) film, in which adhesion is improved by continuously changing a composition from the substrate to the amorphous carbon (DLC) film.